Improvement in speaking-telephones



T. A. WATSON. Speaking-Telephones.

No. 217.561. Patented July 15, 1879..

' f7 9km NFETERS. PNOTO-LITHOGRAPHER, WASHINGTONv D C.

UNITED STATES PATENT OEEIo THOMASQA. WATSON, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN SPEAKlNG-TELEPHONES.

Specification forming part of Letters Patent No. 217.561, dated July 15,1879 application filed May 21, 1879.

To all whom it may concern:

Be it known that I, THOMAS A. VVATSON, of Boston, in the State ofMassachusetts, have invented an Improvement in Speaking-Telephones, ofwhich the following is a specification.

It is common to use a piece of carbon as one of the electrodes of aspeaking-telephone, and hitherto considerable trouble has arisen fromthe imperfect electrical attachment of the carbon to the metal by whichit is supported.

To remedy this evil is the object of this invention; and the inventionconsists in spinning a brass socket upon the carbon.

I have applied this invention to an instrument known as BlakesTelephone, or Blakes Tra-nsmitter,in which oneof the electrodes consistsof a piece of carbon attached to a heavy brass knob or button, in turnattached to one end of a watch-spring.

The drawings represent my improved construction, Figure 1 being aninverted plan, and Fig. 2 a sectional elevation, of the said carbon,brass button, and spring.

The button is marked a, the carbon 0, the spring 01, and b is the boltby which the brass button is secured to the spring.

The method of construction is as follows:

:The carbon is pressed or cut to a cylindrical shape, and a slightgroove made around it, as

shown in Fig. 2. A hole is then bored alittle way into a brass button ofa diameter equal to that of the carbon cylinder, and the carbon havingbeen placed in the hole the brass is spun up into the groove, as shown.The spring and brass button are then bolted together, as shown.

This invention is applicable to any electrical apparatus in which carbonis used for an electrode.

I claim- The carbon electrode 0, in combination with the brass buttonI), the latter being spun upon the former, substantially as described.

THOMAS A. WATSON.

Witnesses:

W. W. SWAN, H. Gr. OLMsTEn.

